This invention relates to the improvement of a voice presetting system in electronic musical instruments such as electronic organs.
In this specification, the term "musical tone signals" as herein used is intended to designate all of the signals related to the formation of sounds or musical tones produced by electronic musical instruments. These signals include not only the signals having spectra, but also original tone signals, modualated tone signals and signals switched by keys. The term "electronic musical instruments" includes for instance electrophonic guitars also.
In general, an electronic instrument is provided with a voice presetting system which is adapted to preset the rates of controlling a plurality of musical tone signals to be mixed and produced, according to the data representing the displacements of a plurality of movable operating members provided for the musical tone signals. For instance, rates in attenuating musical tone signals representing wood, string, flute tones are preset by turning, or displacing in angle, the respective tone levers (manipulating knobs), and the musical tone signals are controlled to the attenuation rates thus preset during the performance, thereby to be mixed and produced as resultant composite musical tones.
In conventional voice presetting systems of the type described above, in addition to tone volume controls provided on a control panel, a number of tone levers are provided on a voice presetting board, and potentiometers whose voltage division ratios are defined by the manipulated positions of the tone levers are connected by switching means to the output sides of a plurality of tone coloring filters (formant circuits) provided at the preceding stage of a musical tone signal mixing circuit.
If it is assumed that rates of attenuating three musical tone signals X, Y and Z are changed stepwise to x.sub.1 -x.sub.4, y.sub.1 -y.sub.4 and z.sub.1 -z.sub.4, respectively, the voice presetting operation is carried out to have, for instance, a first set of attenuation rates (x.sub.1, y.sub.2, z.sub.4), a second set (x.sub.4, y.sub.3, z.sub.1) and so forth. Each of these sets of attenuation rates defines the voltage division ratios of the plurality of potentiometers, that is, the attenuation rates of the respective tone color signals. These potentiometers are connected to the paths of the musical tone signals by the switching means operated by voice presetting operation selecting switches, as a result of which the musical tone signals are controlled and mixed according to the attenuation rates thus preset to obtain the desired voices.
However, this conventional voice presetting system is disadvantageous in the following:
1. The conventional system needs a plurality of rows of tone levers and accordingly a number of tone levers, in order to provide plural sets of manipulated states of the tone levers. Accordingly, the lever presetting operation is rather troublesome, and the larger area of the panel is occupied by the tone levers, this causes an obstruction in making the voice presetting system smaller in size.
2. The conventional system necessitates switching contacts whose number is equal to the number of musical tone signals to be controlled times the number of tone levers to be preset, and therefore the electrical wiring is inevitably complicated, which leads to an obstruction in manufacturing the voice presetting system smaller in size and higher in reliability.
3. With the movable members such as e.g. tone levers whose number is equal to the number of musical tone signals to be controlled thereby, the number of the preset combination, or set of control rates, is only one. Accordingly, increasing the number of the sets of control rates cannot be attained without greatly increasing the number of tone levers and the switching means. However, the increase of the number of these elements is naturally limited to some extent. Therefore, performances on the electronic musical instrument having the conventional system are liable to be insufficient in musical variation.